Original Article Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis – a preliminary study q Riva Tauman a , Ariel Many b , Varda Deutsch c , Shlomit Arvas a , Jessica Ascher-Landsberg b , Michal Greenfeld a , Yakov Sivan a,⇑ a Pediatric Sleep Center, Dana Children’s Hospital, Tel Aviv Souraski Medical Center, Tel Aviv University, Israel b The Department of Obstetrics and Gynceology, Lis Maternity Hospital, Tel Aviv Souraski Medical Center, Tel Aviv University, Israel c The Department of Hematology, Tel Aviv Souraski Medical Center, Tel Aviv University, Israel article info Article history: Received 15 June 2010 Received in revised form 17 August 2010 Accepted 6 September 2010 Available online xxxx Keywords: Snoring IL-6 Erythropoietin Nucleated RBCs Pregnancy Sleep disordered breathing Fetus abstract Objective and background: Snoring is common among pregnant women and early reports suggest that it may bear a risk to the fetus. Increased fetal erythropoiesis manifested by elevated circulating nucleated red blood cells (nRBCs) has been found in complicated pregnancies involving fetal hypoxia. Both eryth- ropoietin (EPO) and interleukin-6 (IL-6) mediate elevation of circulating nRBCs. The intermittent hypoxia and systemic inflammation elicited by sleep-disordered breathing (SDB) could affect fetal erythropoiesis during pregnancy. We hypothesized that maternal snoring will result in increased levels of fetal circulat- ing nRBCs via increased concentrations of EPO, IL-6, or both. Methods: Women of singleton uncomplicated full-term pregnancies were recruited during labor and completed a designated questionnaire. Umbilical cord blood was collected immediately after birth and analyzed for nRBCs, plasma EPO and plasma IL-6 concentrations. Newborn data were retrieved from med- ical records. Results: One hundred and twenty-two women were recruited. Thirty-nine percent of women reported habitual snoring during pregnancy. Cord blood levels of circulating nRBCs, EPO and IL-6 were significantly elevated in habitual snorers compared with non-snorers (p = 0.03, 0.005 and 0.01; respectively). No differences in maternal characteristics or newborn crude outcomes were found. Conclusions: Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis manifested by increased cord blood levels of nRBCs, EPO and IL-6. This provides preliminary evidence that maternal snoring is associated with subtle alterations in markers of fetal well being. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction Self-reported snoring is common among pregnant women dur- ing the third trimester with a prevalence of 14–46% compared with 4% in age-matched non-pregnant women [1–5]. The clinical outcome of snoring and sleep-disordered breathing (SDB) during pregnancy has not been extensively studied, but early reports sug- gest that it may bear a risk to the fetus. Repetitive episodes of obstructive events during sleep give rise to cyclic episodes of maternal hypoxemia and sleep disruption. In addition, hyperten- sion and peripheral vasoconstriction, commonly observed in SDB, have been shown to be associated with reduced placental delivery to the fetus. Indeed, in animal models, exposure to intermittent hypoxia during pregnancy leads to fetal growth restriction, fetal bradycardia and decreased fetal breathing movements [6–8]. How- ever, human studies have, thus far, revealed conflicting results. In a large scale study, Franklin found that self-reported habitual snor- ers had higher frequency of offspring with lower Apgar scores and small-for-gestational-age infants compared with non-snorers [2]. These findings were in contrast to a previous report in which no differences in fetal outcome were found [1]. Nucleated red blood cells (nRBCs) are commonly found in the blood of newborns. They are primarily produced in the fetal bone marrow in response to erythropoietin (EPO) and are stored in the marrow as precursors of reticulocytes and mature erythrocytes. Chronic fetal hypoxia leads to increased fetal erythropoiesis with elevation of circulating nRBCs and EPO concentrations. Indeed, increased umbilical cord levels of EPO and nRBCs have been found in pregnancies complicated by intrauterine growth retardation, maternal hypertension, pre-eclampsia, maternal smoking, and maternal diabetes [9]. 1389-9457/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.sleep.2010.09.005 q This research was supported by The Legacy Heritage Clinical Research Initiative of the Israel Science Foundation (Grant No. 1700/08). ⇑ Corresponding author. Address: Pediatric Sleep Center, Dana Children’s Hospi- tal, Tel Aviv Souraski Medical Center, Tel Aviv University, 6 Weitzman Street, Tel Aviv 64239, Israel. Tel.: +972 36974614; fax: +972 36974634. E-mail address: sivan@post.tau.ac.il (Y. Sivan). Sleep Medicine xxx (2011) xxx–xxx Contents lists available at ScienceDirect Sleep Medicine journal homepage: www.elsevier.com/locate/sleep Please cite this article in press as: Tauman R et al. Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis – a preliminary study. Sleep Med (2011), doi:10.1016/j.sleep.2010.09.005